How to link the download file to a product in Opencart?

Step 1: Log into your OpenCart Dashboard.
Step 2: Go to Products.
Step 3: Click “Insert” to create a new product or click “Edit” next to an existing product.
Step 4: Click on the “links” tab.
Step 5: Scroll towards the bottom of the page, go to the “Downloads” section and select the file you want to be made available on this product.
Step 6: While still editing this product, click on the “Data” tab and scroll down to the section called “Weight”. Enter a weight of “0” (zero) in the field. This tells OpenCart it is a downloadable product.
Step 7: Click on “Save” in the upper right corner